Efficient defrosting on hybrid surfaces with heterogeneous wettability

Abstract

Frosting behavior and dynamic defrosting characteristics of horizontally oriented hybrid surfaces with heterogeneous wettability were experimentally investigated. The developed hybrid surfaces with superhydrophobic patterns built on superhydrophilic background integrated the properties of frost retardation under frosting conditions and fast surface cleaning of residual water upon defrosting. Four types of hybrid surfaces with different pattern spacings were tested in this work. Hybrid surfaces exhibited superior anti-frosting performance compared with that of a bare copper surface but lower than a complete superhydrophobic surface. During defrosting process, surface energy gradient and Laplace pressure gradient enabled by heterogeneous wettability on hybrid surfaces could drive the mobile slush composites on superhydrophobic regions move to superhydrophilic areas to achieve quick cleaning even in the absence of gravity force. The proportion of surface clean time of one full cycle duration on hybrid surfaces was as low as 32.2%–41.5%. Compared to complete superhydrophobic and bare copper surfaces, hybrid surfaces exhibited a significant enhancement on defrost efficiency due to larger three phase contact line length on evaporation-mediated surface cleaning performance, especially the SSH-3 surface, achieving the largest defrost efficiency within the present frost mass range.